TeX belongs to the generation of applications written for environments that didn't offer the sophisticated string and i/o manipulation we nowadays take for granted (TeX was written in Pascal, and the original Pascal standard made no mention of i/o, so that anything but the most trivial operations were likely to be unportable).
When you overwhelm TeX's input mechanism, you get told:
! Unable to read an entire line---bufsize=3000.
Please ask a wizard to enlarge me.
(for some value of '3000' - the quote was from a
comp.text.tex posting by a someone who was presumably
using an old TeX).
As the message implies, there's (what TeX thinks of as a) line in your input that's "too long" (to TeX's way of thinking). Since modern distributions tend to have tens of thousands of bytes of input buffer, it's somewhat rare that these messages occur "for real". Probable culprits are:
The usual advice is to ignore what TeX says (i.e., anything about enlarging), and to put the problem right in the source.
If the real problem is over-long text lines, most self-respecting text editors will be pleased to automatically split long lines (while preserving the "word" structure) so that they are nowhere any longer than a given length; so the solution is just to edit the file.
If the problem is a ridiculous preview section, try using
ghostscript to reprocess the file, outputting a "plain
.eps" file. (Ghostscript is distributed with a script
ps2epsi which will regenerate the preview if necessary.)
Users of the shareware program GSview will find buttons to
perform the required transformation of the file being displayed.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=buffovl